Development of Highly Sensitive Spectroscopy Approach Using a Free-Running Dual-Comb Fiber Laser

Dual-comb spectroscopy (DCS) has attracted considerable attention in recent years owing to its fast data acquisition, high resolution, and broadband spectra coverage, enabled by servo control techniques [1]. To overcome the challenges associated with complexity and large scale of conventional DCS systems, we developed a dual-comb fiber laser [2], [3]. The dual-comb fiber laser is capable of simultaneously generating two optical frequency combs with high relative frequency stability, making it compact and easy operate. However, to effectively average the spectral data obtained using the laser, it is essential to suppress frequency scale fluctuations caused by variations in the repetition rate difference (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta f_{\text {rep }}$</tex>), as well as spectral center frequency fluctuations resulting from changes in the carrier frequency. In this study, digital signal processing was applied to the acquired spectral data to correct the scale and position of the frequency axis.